Electric machine with integrated controller

ABSTRACT

An electric machine may include a housing having a front end and a back end where the front end is the primary mechanical coupling end. The electric machine may include a stator and a rotor arranged within the housing and a shaft connected to the rotor. The shaft may extend out of the front end of the housing and the shaft may be configured to be rotationally driven by the rotor or to rotationally drive the rotor. The electric machine may also include an electronic controller configured to control operations of the rotor and stator and the electronic controller may be mounted on the front end of the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/255,765 filed Jan. 23, 2019, the contents of which are herebyincorporated into this application in its entirety.

The present disclosure claims priority to U.S. Provisional ApplicationNo. 62/620,721, entitled Integrated Electric Machine and PowerController, and filed Jan. 23, 2018 and U.S. Provisional Application No.62/625,544, entitled Integrated Electric Machine and Power Controller,and filed on Feb. 2, 2018, the content of each of which is herebyincorporated by reference herein in its entirety.

TECHNOLOGICAL FIELD

The present application relates to electromechanical devices such aselectric machines including motors, generators, or other machines. Moreparticularly, the present application relates to electric machines thathave drives, electronic speed controls, power controls, or othercontrollers. Still more particularly, the present application relates toelectric machines with particularly arranged and integrated motorcontrollers. Still more particularly, the present application relates toelectric machines with particularly arranged and integrated motorcontrollers having features such as electronic circuit breakers and DCbus pre-charging.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

Electric motors often include a rotating shaft or other articulatingcomponent extending from a front end. The shaft may be adapted formechanically coupling to a power take off device that may use therotational or articulating energy/power from the motor to perform or dowork. The side of the motor where the shaft extends may be a front orprimary mechanical coupling end.

Electronic controllers for electric machines are sometimes mounteddirectly on the machine. The controllers are commonly positioned on arear end the machine (i.e., opposite the front or primary mechanicalcoupling end). By locating the controller on the rear end of themachine, the controller may be out of the way of the drive shaft orother components. Moreover, this arrangement of the controller may allowfor a logical arrangement between the power source and the motor, suchthat electrical power may flow through the controller on its way to themotor. This approach may allow for a clean installation without the needfor control wires or remote signaling between the controller and themotor.

In many cases, the mounting bracket or other mounting features of themotor may be positioned on the rear end of the motor (i.e., the endopposite the front or primary mechanical coupling end). This approachmaintains the mounting screws, bolts, and/or brackets clear of themoving parts of the motor. In situations where a motor controller isintegrated with the motor and arranged on the rear end, the controllerposition may push the functioning parts of the motor (i.e., rotor andstator) further from the mount location creating a more eccentricloading condition on the mount. That is, while this approach maintainsthe controller in line with the power leading to the motor and maintainsthe controller out of the way of the working shaft, the overhung momentof the motor may increase. This eccentric loading can create imbalanceor may cause vibration to be more likely and/or less controllable duringoperation of the motor. Still further, the increased overhung moment cancause additional mechanical stress on the machine housing and the motormount. In some situations, such as on aircraft or other sensitivevehicles, these vibrations may reduce performance or otherwise beproblematic.

Separately, many motors do not have means of protection against shortcircuit either in the motor “bridge” or against short circuit in the DCpower bus. Still further, anti-parallel diodes often prohibit theability to control or protect against reverse current flow that mayoccur when the motor regenerates (due to overspeed, for example) or inthe case of a generator application. Sometimes, fuses may be used toprovide protection, but fuses are generally not fast enough to protectsolid state transistors, or to keep from shutting the entire powersystem down by effectively shorting the DC bus. Fuses are also notcontrollable or resettable. Depending on the motor or machineapplication, this may be a problem. That is, for high reliabilityapplications, such as in electric aircraft where the drive may bepowering a propeller, for example, losses of power without an ability toreset can be dangerous or even catastrophic.

SUMMARY

The following presents a simplified summary of one or more embodimentsof the present disclosure in order to provide a basic understanding ofsuch embodiments. This summary is not an extensive overview of allcontemplated embodiments, and is intended to neither identify key orcritical elements of all embodiments, nor delineate the scope of any orall embodiments.

In one or more embodiments, an electric machine may include a housinghaving a front end and a back end. The front end may be the primarymechanical coupling end. The machine may include a stator and a rotorarranged within the housing and a shaft connected to the rotor andextending out of the front end of the housing. The shaft may beconfigured to be rotationally driven by the rotor or to rotationallydrive the rotor. The machine may also include an electronic controllerconfigured to control operations of the stator and rotor and theelectronic controller may be mounted on the front end of the housing.

In one or more embodiments, an electric machine may include a housingwith a stator and a rotor arranged within the housing. The machine mayinclude a shaft connected to the rotor and extending out of the housingand the shaft may be configured to be rotationally driven by the rotoror to rotationally drive the rotor. The electric machine may alsoinclude an electronic controller configured to control operations of thestator and rotor and the controller may be integrated with the housing.The electronic controller may also include various other features. Forexample, the electronic controller may include an integrated electroniccircuit breaker. Alternatively or additionally, the electroniccontroller may include an insulation monitor configured for identifyingthe presence and source of deteriorating insulation, leakage current, ora short. Alternatively or additionally, the electronic controller mayinclude a load balance feature configured to assist in balancing a loadon the machine. Alternatively or additionally, the electronic controllermay include control features for a variable pitch propeller.Alternatively or additionally, the electronic controller may include apositional control feature configured for use during startup of themachine and the controller may be configured to switch to a sensorlessmode of operation.

While multiple embodiments are disclosed, still other embodiments of thepresent disclosure will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. As will be realized, thevarious embodiments of the present disclosure are capable ofmodifications in various obvious aspects, all without departing from thescope of the present disclosure. Accordingly, the drawings and detaileddescription are to be regarded as illustrative in nature and notrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter that is regarded as formingthe various embodiments of the present disclosure, it is believed thatthe invention will be better understood from the following descriptiontaken in conjunction with the accompanying Figures, in which:

FIG. 1 is a perspective side/front view of a machine with an integratedcontroller, according to one or more embodiments.

FIG. 2 is a perspective side/rear view of a machine with an integratedcontroller, according to one or more embodiments.

FIG. 3 is a cross-sectional view of a machine with an integratedcontroller, according to one or more embodiments.

FIG. 4 is a cross-sectional view of a machine with a duplex frontbearing, according to one or more embodiments.

FIG. 5 is a schematic diagram of a controller architecture, according toone or more embodiments.

FIG. 6 is a schematic circuit diagram of a controller with an electroniccircuit breaker, and optionally, integrated DC bus pre-charge function,according to one or more embodiments.

FIG. 7 is a schematic cross-sectional diagram of an electric machinehaving a dual control, for a variable pitch mechanism, according to oneor more embodiments.

FIG. 8 is a schematic cross-sectional diagram of an electric machinehaving an integrated fan providing for radial flow, according to one ormore embodiments.

FIG. 9 is a schematic cross-sectional diagram of an electric machinehaving an integrated fan providing for axial flow, according to one ormore embodiments

DETAILED DESCRIPTION

The present application, in one or more embodiments, includes anelectric machine (e.g., motor or generator) with an integratedcontroller where the controller is mounted or arranged on a front orprimary mechanical coupling end of the electric machine. This type ofelectric machine may be particularly suitable for powering aircraft suchas drones, personal aircraft, or other aircraft such as, for example,helicopters, quadcopters, or other hover-type aircraft as well asairplanes or other fixed wing aircraft. In these situations, theabove-described electric machine may include a controller positioned ona front of the machine such that it is arranged between the electricmachine and the propeller, for example. This position of the controllermay be on the opposite side of the machine from the machine mountingsurface. This arrangement of the controller may have several advantages.For example, where the machine mount is provided on a back end of themotor, the controller being mounted on the front end may avoid creatingadditional moment between the mount location and the relatively heavyworking elements of the machine. Accordingly, the heavier movingportions of the machine may be in a same or similar position to machinewithout an integrated controller and, as such, the machine may include asimilar overhung moment. This may avoid increased mechanical stress andvibration, which is highly advantageous for aviation and in othercontexts. Moreover, the controller may be relatively more sensitive toheat as compared to the portions of the machine such as therotor/stator. The controller being mounted on the front end of themachine may more fully expose the controller to flowing air or otherfluid from a propeller, fan, or other driven element allowing for bettercontrol of the controller temperature. In some embodiments, the powertransistors within the controller may be arranged about a perimeter ofthe controller and, as such, may take advantage of the higher coolingeffects of the position of the controller. In short, the presentlydisclosed electric machine may have a reduced weight, reduced cablingweight and losses, reduced EMI, improved controllability, improvedsensing and monitoring, improved cooling, and improved ease of use.

The present application, in one or more embodiments, may also relate toa machine and/or controller having an integrated electronic circuitbreaker. This feature may allow for power interruptions, but may also bequickly resettable. The electronic circuit breaker may also include anability to control current reversal and may include a pre-chargefeature. Additional features may include a bearing life estimator orother maintenance and/or failure anticipating technologies.

Referring now to FIG. 1, a perspective side/front view of a machine 100with an integrated controller is shown. FIG. 2 shows a side/rear view ofthe machine and FIG. 3 shows a cross-sectional view. The electricmachine 100 may be configured as a motor, for example, for convertingelectrical energy into rotational energy by spinning a shaft or otherelement. Alternatively, or additionally, the electric machine 100 mayfunction as a generator by creating electrical energy from rotationalenergy as in the case of regenerative breaking or other power generationsituations. Furthermore, in some applications, the machine may alternatebetween motoring and generating, for example, in a vehicle withregenerative braking. The machine 100 may include an electrical powerand/or communications interface 102, a housing 104, a rotor 106, astator 108, a shaft with a power take-off element 110, and a controller112. As shown, the controller 112 may be arranged on the same end of themachine 100 as the power take-off element 110 and opposite the back endor mounting end of the machine 100. That is, for example, the controller112 may be arranged on the front or primary mechanical coupling end ofthe machine (e.g., between the machine and a propeller).

The housing 104 of the machine 100 may be configured for enclosing themoving parts and other components of the machine, for providing a mountfor securing the machine, and for providing cooling of the machine. Thehousing 104 may define an interior and an exterior of the machine andmay include a main body portion 114, a rear end bell 116, a front endbell 118, and a controller housing 120. As shown, the main body portion114 may be substantially cylindrically shaped forming a peripheral wallwith a front rim and a back rim. The cylindrically shaped peripheralwall may be well suited for supporting the stator portions of themachine. The peripheral wall may also include cooling fins or elements122 extending radially outward therefrom. Additionally or alternatively,the cooling fins or elements 122 may include axially extending fins orhelical shapes may be used. The cooling fins or elements may be adaptedto conduct heat away from the machine and to increase the availablesurface area of the peripheral wall to better dissipate heat from themachine to the surrounding environment. Each of the front rim and theback rim may include mounts, tabs, or bosses 124, arranged around aperimeter thereof. The mounts or bosses 124 may be adapted to receivescrews, bolts, or other fasteners for securing the front end bell 118and rear end bell 116 of the housing.

The rear end bell 116 of the housing 104 may be a substantially planarelement configured to close off the back side of the peripheral wall andprovide a support point for the rotor and/or shaft portion of themachine. As shown the rear end bell 116 of the housing 104 may include arear bearing 126 arranged on an inside surface thereof. The rear bearing126 may be arranged within a bearing seat on an inside surface of therear end bell and the rear bearing may be configured for securing theposition of the shaft 128 while allowing the shaft 128 to rotatesubstantially freely. While the shaft 128 is shown to terminate at theinside surface of the rear end bell, in one or more embodiments, theshaft may pass through the rear end bell to provide power to secondaryelements. Accordingly, the rear bearing 126 may be arranged in a bearingseat that allows the shaft of the machine to pass through the rear endbell. The rear end bell may include tabs or bosses arranged around aperipheral edge thereof configured for aligning with the bosses on theperipheral wall of the housing and allowing the rear end bell to besecured to the peripheral wall. As shown in FIG. 2, the rear end bellmay also include one or a series of mounting holes 130. The holes may bethreaded bores extending into the rear end bell allowing the rear endbell, and thus, the machine, to be attached to a mounting bracket,mounting plate, or other mounting element.

The front end bell 118 may function similarly to the rear end bell 116and may be configured to close off the front side of the peripheral walland provide a support point for the rotor and/or shaft portion 128 ofthe machine as the shaft passes through the front end bell 118. Asshown, the front end bell 118 may include a front bearing 132 arrangedon an inside surface thereof. The front bearing 132 may be arrangedwithin a bearing seat on an inside surface of the front end bell 118 andthe front bearing 132 may be configured for securing the position of theshaft 128 while allowing the shaft to pass through the bearing androtate substantially freely. The front end bell may include tabs or lugsarranged around a peripheral edge thereof configured for aligning withthe lugs on the peripheral wall of the housing and allowing the frontend bell to be secured to the peripheral wall.

The general geometry of the machine and its housing may be particularlyadapted for arranging the controller on the front end of the machine.For example, in one or more embodiments, the machine and its housing mayhave a length 134 measured from the front end to the back end that isshorter than the diameter 136 of the housing 104. This type of machinegeometry may provide for a relatively large surface area on the ends ofthe machine for arrangement of the integrated controller 112. That is,the larger surface area of the machine on the front end may allow thecomponents of the controller to be spread out laterally across thesurface without adding a lot of length to the shaft. For example, wherethe shaft extends from the front end of the machine and operates apropeller, a clearance space between the back side of the propeller andthe front face of the machine may be needed. By providing a relativelybroad front surface on the machine, the controller may be placed therewithout a need to extend the shaft to maintain the clearance space. Inthe case of aircrafts and propellers, avoiding lengthening of the shaftcan be valuable due to vibration and control concerns.

The controller housing 120 may be arranged around and/or may beintegrated into the front end bell. As shown in FIG. 3, the controllerhousing may be an annularly shaped housing providing an annular spacebetween the front end bell 118 and the primary power take off element110 for arranging controller circuitry, control boards and the like. Thecontroller housing 120, like the peripheral wall, may include aplurality of cooling fins or elements 122. The cooling fins may beadapted to conduct heat away from the machine and to increase theavailable surface area of the controller housing to better dissipateheat from the controller and/or machine and to the surroundingenvironment. The controller housing 120 may provide a secured andprotected cavity on the front side of the machine and around the driveshaft or power take-off element for controller components to bearranged. The controller components can, thus, be arranged in closeproximity to the machine and without interrupting or altering therelative position of the heavier parts of the machine and the mountingportions of the machine. The close proximity of the controller to themachine provides for sensors to be easily integrated. For example,position, temperature, and/or vibration sensors may be included. Inaddition, and as shown, the controller power transistors, described inmore detail below, may be distributed around the outer diameter of thehousing. The transistors, including both main transistors andtransistors for an electronic circuit breaker, may be arranged in aradial pattern around the peripheral edge of the front of the machine.The positions of the transistors at or near the outer diameter of thehousing and in close proximity to the cooling fins or elements 122 mayallow for a highly efficient heat transfer and may allow the transistortemperature to be more easily controlled and avoid overheating. It is tobe appreciate that while the particular embodiment shown shows thecontroller arranged on in an area between the front end bell and adedicated controller housing, a more integrated approach may also beused. For example, the front end bell may be a double wall structurehaving a cavity for arrangement of the controller components. In stillother embodiments, the peripheral wall of the housing 104 may belengthened in a forward direction providing more room within the housingfor controller components to be arranged on an inside surface of thefront end bell. Still other approaches to providing a protected spacefor the controller components may be used.

As mentioned, the machine geometry having a relatively broad diameterrelative to its length may allow for the front placement of thecontroller. The controller 112 and its controller housing 120 may thushave a relatively flat and/or thin shape arranged across the front endof the machine. The controller housing 120 and the controller 112 may bearranged in an annular pattern to avoid interference with the shaftextending from the machine. However, and in addition, due to the broadsurface area of the front end of the motor, the controller housing 120and the controller 112 may be relatively thin and/or pancake shaped innature.

The electrical power and/or communications interface 102 may be seen inFIGS. 1 and 2. The electrical and/or communications interface 102 may beconfigured for delivering or receiving electrical power to/from themachine 100. As shown, the interface 102 may include a junction boxarranged on the peripheral wall of the housing. The interface mayinclude jacks or ports for connecting electrical power or communicationsleads from a system the machine is being used in conjunction with. Forexample, in the case of an aircraft, the communications interface may beconfigured for connecting to aircraft avionic controls. In one or moreembodiments, the interface may be for connecting other types ofcontrols. Where, for example, the machine is used with a wheeled vehicleand the machine is used for powering one or more drive wheels, theinterface may be adapted to receive drive and/or navigational controls.

With further reference to FIG. 3, the machine 100 may include a rotor106 and a stator 108. As shown, the stator 108 may be arranged on aninner surface of the peripheral wall of the housing 104 and may beadapted for magnetically interacting with the rotor to rotationallydrive the rotor 106. More particularly, the stator 108 may include aseries of coils arranged around the inside surface of the housing 104.The series of coils may be in electrical communication with a powersource via a controller 112 to energize the coils and create magneticfields to drive the rotor 106. The rotor 106 may be arranged within thestator 108 and may be adapted to rotate substantially freely within thestator. For example, the rotor may include a hub arranged on the shaft128 which may form a wheel. The wheel may include a plurality of magnetsarranged on the peripheral surface thereof for magnetically interactingwith the stator.

As mentioned above, the shaft 128 may be supported on the housing 104 byone or more bearings 126/132. The system of bearings may be adapted toreceive and resist both radial and axial loads so as to maintain theposition of the shaft 128. In one or more embodiments, as shown in FIG.3, a front bearing 132 may be provided that is supported by the frontend bell and a second rear bearing 126 may be provide that is supportedby the rear end bell. In this embodiment, the front bearing may handlethe axial load (i.e. thrust) “pulling” on the shaft and the rear bearingmay handle the load “pushing” on the shaft. That is, and as shown, theshaft 128 may include a rib or ribs 138 at a location inside the frontbearing and the bearing may function with the ribs to prevent forwardmotion of the shaft relative the bearing and, thus, relative to themachine. Both bearings in this embodiment may be adapted to resistradial loads. In one or more embodiments, the front bearing 232 mayinclude a duplex pair bearing arrangement. This type of bearing mayprovide a higher degree of mechanical load capacity and rigidity. Inthis embodiment, the duplex bearing 232 may resist thrust load in bothdirections. That is, as shown in FIG. 4, the shaft may include a rib orcollar 238 at a position inside the front end bearing that may interactwith the bearing to resist forward motion of the shaft 228 relative tothe bearing and, thus, the machine. In addition, the shaft may include athreaded portion outside the housing or outside the bearing and a pairof nuts 239 may be threaded onto the shaft to secure the position of theshaft relative to the housing. A such, the internal rib or collar 238and the outer nuts 239 may secure the position of the shaft 228 relativeto the bearing. In this embodiment, the rear end bearing 226 may bedesigned to resist solely radial loads. However, a rear bearing thatresists radial loads and axial loads may also be used. Still otherembodiments with various bearing configurations may be used. It is to beappreciated that while FIG. 4 does not show an integrated controller,the integrated controller features of FIG. 3 may be provided inconjunction with the duplex bearing system of FIG. 4.

In any case, the bearings 126/226 and 132/232 may allow for the shaft torotate substantially freely and, as such, the rotor may be substantiallyfree to rotate. When power is activated to the machine, the stator maybecome energized and may magnetically interact with the rotor to rotatethe rotor. While one particular type of machine has been described,still other types of machines may be used, including both radial andaxial flux machines. Still further, the magnet shapes on the stator orrotor may be sized and shaped for greatest efficiency. In one or moreembodiments, protruding magnets such as those described in U.S. patentSer. No. 15/149,744 entitled Permanent-Magnet Machines UtilizingProtruding Magnets and filed on May 9, 2016 may be provided. The contentof this application is hereby incorporated by reference in its entirety.

The shaft 128/228 may be arranged substantially along a centerline ofthe machine and may be configured to rotate based on rotational powerfrom the rotor/stator. The shaft may be supported by the bearings asmentioned and may extend out the primary mechanical coupling end orfront of the housing and may also extend out the back end of themachine. The shaft may be a solid shaft. Alternatively, the shaft may behollow to allow for the passage of control or sensing elements to themechanical coupling end of the shaft. In one or more embodiments, forexample where a variable pitch propeller is used, the hollow shaft mayallow for control elements to pass through the shaft to provide controlof the blade pitch. In one or more embodiments, the shaft 128/228 mayinclude a tapered tip allowing for a secure press fit of the powertake-off element 110.

A power take-off element 110 may be provided allowing the rotationalpower from the rotating shaft 128 to be put to use to perform work. Inone or more embodiments, the power take-off element 110 may include aflange/hub arranged on the shaft allowing for the attachment of apropeller or a plurality of propeller blades. In one or moreembodiments, the power take-off element may include a variable pitch andfeathering hub allowing for attachment and control of a variable pitchand feathering propeller. The hub/flange may include a bore extendingtherethrough and a key or keyway for engaging the shaft 128 of themachine to transfer the torque from the shaft to the hub. The hub/flangemay be arranged on the shaft and a hub nut may be threaded onto theshaft to secure the hub/flange to the shaft. The shaft may also protrudefrom the rear end to provide rotational power for secondary functions ordevices, such as sensors, clutches, or brakes, for example.

The controller 112 and the components thereof may be arranged on thefront or primary mechanical coupling end of the machine 100 and withinthe controller housing 120. The controller 112 may be configured tooperate the machine and/or the equipment or devices receiving power fromthe machine. For example, in the case of an aircraft or other devicewith a variable pitch propeller, the controller 112 may function tocontrol the machine in addition to the pitch of the propeller bladessecured to the hub/flange. The controller 112 may perform still otherfunctions.

As shown in FIG. 5, the controller 112 may include a control board 140and a power board 142. The power board 142 may be configured forinterfacing with and managing the power being provided to the machinefrom a power bus 144, such as an aircraft power bus or another power buson another supported or powered vehicle, device, or system. That is,while this particular controller is being described as suitable for anaircraft, the machine described herein may be suitable for use in avariety of situations and on other types of equipment, machines,vehicles, or systems. The power board may include bus capacitors 146,power transistors 148, including but not limited to insulated gatebipolar transistors (IGBTs), transistor gate drivers, and one or moresensors 150. The sensors may include current and/or voltage sensors forexample.

The control board 140 may be configured for converting and controllingthe incoming power to the machine and adjusting the speed and or torqueof the machine, for example. The controller 112 may also be configuredfor more sophisticated controls such as controlling the pitch of avariable pitch propeller or controlling other aspects of a vehicle,aircraft, or other system. As such, the control board 140 may includeparticular components for such control. In one or more embodiments, thecontrol board 140 may include several different components forinterfacing to sensors including, for example, temperature 152,vibration (accelerometer) 178, and position sensing inputs 154(including but not limited to Hall Effect Sensors). The control board140 may also include one or more digital signal processors, or otherprocessors 156. The control board may also include gate driver circuitry158 arranged between the power transistors and the processor, and thecontrol board may also include various communication interfaces such asCAN 160, or RS-485 serial port 162 for interfacing with aircraftavionics, for example. Additionally, a second processor or additionalprocessors 164 may be used to manage the communications or otherfunctions, separate from the main machine control processor. The controlboard 140 may also include various ancillary power supplies 166 to powerthe components internal to the controller, as well as receive controlpower from the avionics connector 168.

Turning now to FIG. 6, a schematic electrical diagram for use with thepresent machine is shown. As shown, power for the drive may be providedas a positive and negative power bus 144. The electrical system mayinclude one or more drive bridges 170 each including a plurality oftransistors 148 arranged in pairs across the positive and negative busesof the power bus 144. The bridges may be arranged in parallel with oneanother. In addition, DC bus capacitance 146 may be provided by aplurality of capacitors, each arranged in parallel with a pair oftransistors to form a bridge. Phase connections 172 may be providedbetween the transistors for connection to the electric machine that thecontroller is driving. As shown, the system may be provided with onebridge consisting of three pairs of transistors to drive a three phaseelectric machine winding. However, in other embodiments the system mayhave six pairs of transistors configured as two bridges to drive twoseparate three phase windings, or one six phase electric machinewinding, for example. Other numbers of transistor pairs, bridges, andmachine windings are also possible, which can provide a higher level ofperformance and redundancy should one or more of the bridges fail.

The system may be provided with an electronic circuit breaker 174 and/ora pre-charge network 176. The electronic circuit breaker (ECB) 174 maybe provided by a pair of transistors arranged along the positive powerbus as shown. Alternatively or additionally, the ECB may be arrangedalong the negative power bus. The pre-charge network 176 may include adiode and a resistor arranged in parallel with the positive power bus,and in other embodiments the negative power bus, and, in particular, atleast one of the transistors forming the electronic circuit breaker. Inone or more embodiments, the transistors may include MOSFETs (as shown).Alternatively, the transistors may be IGBTs or other power switchingdevices.

It is to be appreciated that by integrating the ECB into the drive, ahighly reliable power system may be implemented without the need toinstall external protection (i.e., fusing or ECB). Also, the mentionedcooling system for the main power transistors 148 may be used to coolthe ECB 174. For example, the transistors for the ECB 174 may bearranged in a similar location (i.e., around the peripheral edge of themachine) as the main power transistors 148 to take advantage of thecooling effect of cooling elements on the housing and the controllerlocation. The drive may also include an established digitalcommunications bus to the overall system, so the control of the ECB aswell as health and status monitoring (Voltage, Current, Power,Temperature) are easily incorporated without additional cost orcomplexity. Moreover, integrating the ECB into the drive may allow thedirection of power flow to be controlled. For example, if noregenerative power is to be allowed in the system (i.e., power returnedto the DC bus from the drive), only the Q2 transistor may be turned onand the Q1 transistor left off. Alternatively, if the drive is beingused strictly as a generator, only Q1 may be turned on and Q2 left off.If bi-directional power flow is desired, both Q1 and Q2 may be turnedon. This may be the normal mode of operation.

The optional DC bus pre-charge function may operate in conjunction withthe ECB components. Pre-charge may allow for bringing the DC buscapacitors (C1-C3) 146 up to voltage in a controlled manner withoutdrawing a large amount of current from the DC bus. This may be useful,for example, if the motor drive is brought on-line while the DC bus isfully energized. If there were no pre-charge function, and the ECB werejust switched on, there would be a very large inrush of current chargingC1-C3, which could cause damage to the ECB components as well as disruptother equipment on the bus. In one embodiment, diode D1 and resistor R1form a pre-charge network which will slowly charge C1-C3 when just Q2 ofthe ECB is turned on. Then, after charge is complete, Q1 may be turnedon and the drive may be ready for normal bi-directional operation. Otherembodiments of implementing the pre-charge function are possible, suchas operating Q1 and Q2 in the linear region to charge C1 in a controlledmanner.

Additional features of the system may include features associated withpreviously mentioned sensors such as the integrated accelerometer 178and the position sensors 154. In additional further features such asinsulation monitoring 182, integrated control of a variable pitchpropeller 184, and an integrated cooling fan 186 may also be provided.Each of these will be discussed in turn.

The integrated accelerometer 178 may include an accelerometer built intothe controller 112. The accelerometer 178 may be used to monitorvibration. The monitored vibration may be used to help determine thehealth of the bearing and mechanical systems. For example, as bearingswear, vibration may increase and, as such, varying amounts of vibrationmay be used to assess the condition of the bearings over time. A bearinglife estimator 190 may be provided as a part of the controller 112(i.e., as part of the processor 156) and the amount of vibration sensedby the integrated accelerometer may be one of the inputs received by thebearing life estimator. The bearing life estimator 190 may also useother factors such as the amount of time since bearing replacement,temperature, speed, flight hours or other use, and the like. Theaccelerometer readings and/or the results of the bearing life estimatormay be reported to the external control system over the digitalcommunications bus, for example.

In addition to bearing life, the accelerometer 178 may be used tobalance a load on the machine, such as, for example, a propeller securedto the shaft of the machine. The accelerometer 178 and position sensors154 may be used to correlate vibration (acceleration) with rotorposition. This information may also be provided over the digitalcommunication bus to determine the location and the amount of materialto be added (or removed) from the propeller or other load in order tobring the propeller or other load into balance. A load balance feature188 may be built into the processor 156 of the controller 112, forexample.

Position sensors 154 may be provided to allow for control of motorcommutation and speed. As shown in FIG. 3, the sensor may be arranged onan inside surface of the housing and may sense the rotor position basedon magnetic sensing of the rotor magnets. In addition, the absoluteposition of the propeller or other load may be determined. In one ormore embodiments, this position sensing may be used together with thevibration to assist with balancing the propeller or other load.Alternatively, or additionally, the position sensors may be used to holdthe propeller in a specific orientation during the flight of theaircraft or during other operations. Still further, the controller canuse the sensors to start the motor, but can continue to operate in asensorless mode if the position sensors fail and, thus, providing a highlevel of reliability. For example, the motor may be started morereliably using the sensor because the rotor position can be determinedfrom the sensors. Moreover, once the motor is running, the rotorposition may be determined by other methods such as back-EMF or voltagemonitoring. As such, if the position sensors were to fail after themotor is running, the controller may continue to operate using a“sensorless” method. That is, the controller may include a rotorpositional sensing feature for sensing the position of the rotor andthat may be used at startup. Then, and optionally, the controller mayswitch to sensorless operation if, for example, the sensors were tofail.

In one or more embodiments, the position sensors 154 may be used tocontrol the radial orientation of the shaft, particularly duringstoppages. For example, where a particular orientation of a propellerarranged on the shaft is desired, the position sensors may be used toassess the position such that a rotor positional control feature of themachine/controller can rotate the shaft and position the propelleraccordingly. In one example, some aircraft may use propellers to elevatean aircraft until the aircraft is in a suitable position to move or flylaterally. In some embodiments, other systems or devices may be used topropel the aircraft laterally and the propeller may cease functioningonce the other systems take over. In this situation, it may be desirableto rotate the propeller to a position to minimize drag or otherinterference. In this embodiment, the position sensors may be used toassess the position of the rotor/shaft and communicate that position tothe rotor positional control feature such that machine/controller may beinformed sufficiently to rotate and hold the propeller to the desiredposition.

The insulation monitoring feature 182 may be used to identify shorts orleakage current paths inside a motor, for example, between the high andlow voltage sections of the motor. For example, it can be important todetect if one of the high voltage DC inputs or AC motor leads becomesshorted to the chassis (ground). At the system level, while a problemmay be identified, the source of the problem cannot. That is, at thesystem level, the particular motor with the problem may not beidentified. If there are eight motors on a single DC bus, for example,one short may create a problem, but identifying which motor is thesource of the problem is not clear. An insulation monitoring feature 182may be built into the controller 112 to monitor each motor and it canreport over the digital communications bus, which motor has the problem.

As mentioned, the controller may be multi-purpose. That is, for example,the controller may be capable of operating the motor and controlling themotor speed and or torque. However, the controller may also function tointerface with the load on the motor and control further aspects orfeatures of the load. For example, as shown in FIG. 7, the controllermay be a dual control and may function to control the rotational speedof the propeller, but also the pitch of the blades on the propeller.This may involve a primary machine 100 with a rotor and a stator and asecondary or pitch control machine 300 with a rotor and a stator. Thecontroller 312 may be configured for controlling each of these machinesto control the power being provided by the propeller through the speedof the propeller and the pitch of the blades of the propeller. This mayreduce or eliminate the need for a separate controller for this purpose.As shown, the mechanism to control the propeller may be built into themotor and may include a secondary generator 300 on the motor shaft topower the pitch control mechanism 302, as opposed to a mechanical systemthat operates with linkages through the hollow shaft.

In one or more embodiments, the system may include an integrated fan.For example, the fan may include an integrated exterior fan such as aplurality of axial flow fan blades mounted on a hub on the shaft outsidethe housing. This may be used when, for example, the machine is notbeing used with a propeller. Additionally or alternatively, and as shownin FIGS. 8 and 9, the system may include an integrated internal fan. Forexample, and as shown in FIG. 8, the rotor hub structure may be used asa radial flow (centrifugal) blower 192. In this embodiment, the spokesof the rotor may include fan blades arranged to throw air radially asthe rotor rotates. For example, relatively flat blades arranged in aplane perpendicular to the plane of the rotor may be provided. In otherembodiments, similarly arranged blades may be used where thecross-section of the blade is cupped or has a shape other than flat. Inone or more other embodiments, and as shown in FIG. 9, the rotor hubstructure may be used as an axial flow blower 194. In this embodiment,the spokes of the rotor may include fan blades canted at angle such thatrotation of the rotor causes air to flow across the plane of the rotor.In either case, this may provide airflow inside the motor providing forinternal cooling of the rotor, stator, and controller. That is, ratherthan relying solely on the cooling fins or elements to dissipate heatfrom the motor and the controller, the rotating portion of the motor maybe used to circulate air inside the motor further dissipating the heatfrom the components.

The several features and sensors of the controller may be suitable formonitoring many characteristics and properties of the machine and mayoften be relied on for protecting the machine from damage. For example,excessive temperatures, excessive vibration, current, speed, orpositional misalignment may be identified by the sensors and may be usedto identify improper or unsuitable operation and may trigger shutdown ofthe machine before damage to the machine occurs. However, in the case ofan aircraft, losses of power may be more catastrophic than damage to themachine. Accordingly, the controller may include an assessment tool 196allowing for continued operation during improper or unsuitable operationof the machine such that the aircraft may continue to receive poweruntil it can be safely landed. In one or more embodiments, theassessment tool may be in communication with the one of more sensorsincluding the temperature sensor, the accelerometer, and/or the positionsensor. The assessment tool 196 may have a series of thresholds (i.e.,one for each sensor) above which operation of the machine is consideredto be improper or unsuitable. When these thresholds are exceeded, theassessment tool may indicate a dangerous condition and may trigger analert to the user to land the aircraft or other vehicle. The assessmenttool may limit the power to the machine in a manner that allows forcontinued operation of the machine, but also limits the amount of damagethat the machine may incur. The assessment tool may continue to monitorthe sensor results and upon landing of the aircraft, if the sensorresults continue to exceed the threshold, the machine may be shutdown.

For purposes of this disclosure, any system described herein may includeany instrumentality or aggregate of instrumentalities operable tocompute, calculate, determine, classify, process, transmit, receive,retrieve, originate, switch, store, display, communicate, manifest,detect, record, reproduce, handle, or utilize any form of information,intelligence, or data for business, scientific, control, or otherpurposes. For example, a system or any portion thereof may be aminicomputer, mainframe computer, personal computer (e.g., desktop orlaptop), tablet computer, embedded computer, mobile device (e.g.,personal digital assistant (PDA) or smart phone) or other hand-heldcomputing device, server (e.g., blade server or rack server), a networkstorage device, or any other suitable device or combination of devicesand may vary in size, shape, performance, functionality, and price. Asystem may include volatile memory (e.g., random access memory (RAM)),one or more processing resources such as a central processing unit (CPU)or hardware or software control logic, ROM, and/or other types ofnonvolatile memory (e.g., EPROM, EEPROM, etc.). A basic input/outputsystem (BIOS) can be stored in the non-volatile memory (e.g., ROM), andmay include basic routines facilitating communication of data andsignals between components within the system. The volatile memory mayadditionally include a high-speed RAM, such as static RAM for cachingdata.

Additional components of a system may include one or more disk drives orone or more mass storage devices, one or more network ports forcommunicating with external devices as well as various input and output(I/O) devices, such as digital and analog general purpose I/O, akeyboard, a mouse, touchscreen and/or a video display. Mass storagedevices may include, but are not limited to, a hard disk drive, floppydisk drive, CD-ROM drive, smart drive, flash drive, or other types ofnon-volatile data storage, a plurality of storage devices, a storagesubsystem, or any combination of storage devices. A storage interfacemay be provided for interfacing with mass storage devices, for example,a storage subsystem. The storage interface may include any suitableinterface technology, such as EIDE, ATA, SATA, and IEEE 1394. A systemmay include what is referred to as a user interface for interacting withthe system, which may generally include a display, mouse or other cursorcontrol device, keyboard, button, touchpad, touch screen, stylus, remotecontrol (such as an infrared remote control), microphone, camera, videorecorder, gesture systems (e.g., eye movement, head movement, etc.),speaker, LED, light, joystick, game pad, switch, buzzer, bell, and/orother user input/output device for communicating with one or more usersor for entering information into the system. These and other devices forinteracting with the system may be connected to the system through I/Odevice interface(s) via a system bus, but can be connected by otherinterfaces such as a parallel port, IEEE 1394 serial port, a game port,a USB port, an IR interface, etc. Output devices may include any type ofdevice for presenting information to a user, including but not limitedto, a computer monitor, flat-screen display, or other visual display, aprinter, and/or speakers or any other device for providing informationin audio form, such as a telephone, a plurality of output devices, orany combination of output devices.

A system may also include one or more buses operable to transmitcommunications between the various hardware components. A system bus maybe any of several types of bus structure that can further interconnect,for example, to a memory bus (with or without a memory controller)and/or a peripheral bus (e.g., PCI, PCIe, AGP, LPC, I2C, SPI, USB, etc.)using any of a variety of commercially available bus architectures.

One or more programs or applications, such as a web browser and/or otherexecutable applications, may be stored in one or more of the system datastorage devices. Generally, programs may include routines, methods, datastructures, other software components, etc., that perform particulartasks or implement particular abstract data types. Programs orapplications may be loaded in part or in whole into a main memory orprocessor during execution by the processor. One or more processors mayexecute applications or programs to run systems or methods of thepresent disclosure, or portions thereof, stored as executable programsor program code in the memory, or received from the Internet or othernetwork. Any commercial or freeware web browser or other applicationcapable of retrieving content from a network and displaying pages orscreens may be used. In some embodiments, a customized application maybe used to access, display, and update information. A user may interactwith the system, programs, and data stored thereon or accessible theretousing any one or more of the input and output devices described above.

A system of the present disclosure can operate in a networkedenvironment using logical connections via a wired and/or wirelesscommunications subsystem to one or more networks and/or other computers.Other computers can include, but are not limited to, workstations,servers, routers, personal computers, microprocessor-based entertainmentappliances, peer devices, or other common network nodes, and maygenerally include many or all of the elements described above. Logicalconnections may include wired and/or wireless connectivity to a localarea network (LAN), a wide area network (WAN), hotspot, a globalcommunications network, such as the Internet, and so on. The system maybe operable to communicate with wired and/or wireless devices or otherprocessing entities using, for example, radio technologies, such as theIEEE 802.xx family of standards, and includes at least Wi-Fi (wirelessfidelity), WiMax, and Bluetooth wireless technologies. Communicationscan be made via a predefined structure as with a conventional network orvia an ad hoc communication between at least two devices.

Hardware and software components of the present disclosure, as discussedherein, may be integral portions of a single computer, server,controller, or message sign, or may be connected parts of a computernetwork. The hardware and software components may be located within asingle location or, in other embodiments, portions of the hardware andsoftware components may be divided among a plurality of locations andconnected directly or through a global computer information network,such as the Internet. Accordingly, aspects of the various embodiments ofthe present disclosure can be practiced in distributed computingenvironments where certain tasks are performed by remote processingdevices that are linked through a communications network. In such adistributed computing environment, program modules may be located inlocal and/or remote storage and/or memory systems.

As will be appreciated by one of skill in the art, the variousembodiments of the present disclosure may be embodied as a method(including, for example, a computer-implemented process, a businessprocess, and/or any other process), apparatus (including, for example, asystem, machine, device, computer program product, and/or the like), ora combination of the foregoing. Accordingly, embodiments of the presentdisclosure may take the form of an entirely hardware embodiment, anentirely software embodiment (including firmware, middleware, microcode,hardware description languages, etc.), or an embodiment combiningsoftware and hardware aspects. Furthermore, embodiments of the presentdisclosure may take the form of a computer program product on acomputer-readable medium or computer-readable storage medium, havingcomputer-executable program code embodied in the medium, that defineprocesses or methods described herein. A processor or processors mayperform the necessary tasks defined by the computer-executable programcode. Computer-executable program code for carrying out operations ofembodiments of the present disclosure may be written in an objectoriented, scripted or unscripted programming language such as Java,Perl, PHP, Visual Basic, Smalltalk, C++, or the like. However, thecomputer program code for carrying out operations of embodiments of thepresent disclosure may also be written in conventional proceduralprogramming languages, such as the C programming language or similarprogramming languages. A code segment may represent a procedure, afunction, a subprogram, a program, a routine, a subroutine, a module, anobject, a software package, a class, or any combination of instructions,data structures, or program statements. A code segment may be coupled toanother code segment or a hardware circuit by passing and/or receivinginformation, data, arguments, parameters, or memory contents.Information, arguments, parameters, data, etc. may be passed, forwarded,or transmitted via any suitable means including memory sharing, messagepassing, token passing, network transmission, etc.

In the context of this document, a computer readable medium may be anymedium that can contain, store, communicate, or transport the programfor use by or in connection with the systems disclosed herein. Thecomputer-executable program code may be transmitted using anyappropriate medium, including but not limited to the Internet, opticalfiber cable, radio frequency (RF) signals or other wireless signals, orother mediums. The computer readable medium may be, for example but isnot limited to, an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system, apparatus, or device. More specificexamples of suitable computer readable medium include, but are notlimited to, an electrical connection having one or more wires or atangible storage medium such as a portable computer diskette, a harddisk, a random access memory (RAM), a read-only memory (ROM), anerasable programmable read-only memory (EPROM or Flash memory), acompact disc read-only memory (CD-ROM), or other optical or magneticstorage device. Computer-readable media includes, but is not to beconfused with, computer-readable storage medium, which is intended tocover all physical, non-transitory, or similar embodiments ofcomputer-readable media.

Various embodiments of the present disclosure may be described hereinwith reference to flowchart illustrations and/or block diagrams ofmethods, apparatus (systems), and computer program products. It isunderstood that each block of the flowchart illustrations and/or blockdiagrams, and/or combinations of blocks in the flowchart illustrationsand/or block diagrams, can be implemented by computer-executable programcode portions. These computer-executable program code portions may beprovided to a processor of a general purpose computer, special purposecomputer, or other programmable data processing apparatus to produce aparticular machine, such that the code portions, which execute via theprocessor of the computer or other programmable data processingapparatus, create mechanisms for implementing the functions/actsspecified in the flowchart and/or block diagram block or blocks.Alternatively, computer program implemented steps or acts may becombined with operator or human implemented steps or acts in order tocarry out an embodiment of the invention.

Additionally, although a flowchart or block diagram may illustrate amethod as comprising sequential steps or a process as having aparticular order of operations, many of the steps or operations in theflowchart(s) or block diagram(s) illustrated herein can be performed inparallel or concurrently, and the flowchart(s) or block diagram(s)should be read in the context of the various embodiments of the presentdisclosure. In addition, the order of the method steps or processoperations illustrated in a flowchart or block diagram may be rearrangedfor some embodiments. Similarly, a method or process illustrated in aflow chart or block diagram could have additional steps or operationsnot included therein or fewer steps or operations than those shown.Moreover, a method step may correspond to a method, a function, aprocedure, a subroutine, a subprogram, etc.

As used herein, the terms “substantially” or “generally” refer to thecomplete or nearly complete extent or degree of an action,characteristic, property, state, structure, item, or result. Forexample, an object that is “substantially” or “generally” enclosed wouldmean that the object is either completely enclosed or nearly completelyenclosed. The exact allowable degree of deviation from absolutecompleteness may in some cases depend on the specific context. However,generally speaking, the nearness of completion will be so as to havegenerally the same overall result as if absolute and total completionwere obtained. The use of “substantially” or “generally” is equallyapplicable when used in a negative connotation to refer to the completeor near complete lack of an action, characteristic, property, state,structure, item, or result. For example, an element, combination,embodiment, or composition that is “substantially free of” or “generallyfree of” an element may still actually contain such element as long asthere is generally no significant effect thereof.

To aid the Patent Office and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants wishto note that they do not intend any of the appended claims or claimelements to invoke 35 U.S.C. § 112(f) unless the words “means for” or“step for” are explicitly used in the particular claim.

Additionally, as used herein, the phrase “at least one of [X] and [Y],”where X and Y are different components that may be included in anembodiment of the present disclosure, means that the embodiment couldinclude component X without component Y, the embodiment could includethe component Y without component X, or the embodiment could includeboth components X and Y. Similarly, when used with respect to three ormore components, such as “at least one of [X], [Y], and [Z],” the phrasemeans that the embodiment could include any one of the three or morecomponents, any combination or sub-combination of any of the components,or all of the components.

In the foregoing description various embodiments of the presentdisclosure have been presented for the purpose of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise form disclosed. Obvious modifications orvariations are possible in light of the above teachings. The variousembodiments were chosen and described to provide the best illustrationof the principals of the disclosure and their practical application, andto enable one of ordinary skill in the art to utilize the variousembodiments with various modifications as are suited to the particularuse contemplated. All such modifications and variations are within thescope of the present disclosure as determined by the appended claimswhen interpreted in accordance with the breadth they are fairly,legally, and equitably entitled.

What is claimed is:
 1. An electric machine, comprising: a housing havinga front end and a back end, the front end being the primary mechanicalcoupling end of the machine; a stator and a rotor arranged within thehousing; a shaft connected to the rotor and extending out of the frontend of the housing, the shaft configured to be rotationally driven bythe rotor or to rotationally drive the rotor; and an electroniccontroller configured to control operations of the stator and rotor andbeing mounted on the front end of the housing.
 2. The electric machineof claim 1, wherein the housing includes a mount surface on the back endof the housing and the front end is opposite the back end.
 3. Theelectric machine of claim 1, wherein the controller comprises aplurality of power transistors distributed along an outer perimeter ofthe controller.
 4. The electric machine of claim 1, wherein thecontroller comprises an integrated electronic circuit breaker.
 5. Theelectric machine of claim 1, wherein the controller comprises apre-charge feature.
 6. The electric machine of claim 1, furthercomprising an integrated interior cooling fan.
 7. The electric machineof claim 1, further comprising an integrated exterior cooling fan. 8.The electric machine of claim 1, further comprising a bearing supportingthe shaft and a bearing life estimator, wherein the bearing lifeestimator is configured for receiving sensor input and for estimating aremaining life of the bearing based on the sensor input.
 9. The electricmachine of claim 1, wherein the controller comprises an assessment toolconfigured for receiving sensor data and limiting operation of themachine when unrestricted operation is deemed unsuitable.
 10. Theelectric machine of claim 1, further comprising an insulation monitorconfigured for identifying the presence and source of electricalinsulation deterioration.
 11. The electric machine of claim 1, furthercomprising a load balance feature configured to assist in mechanicalbalancing of a load on the machine.
 12. The electric machine of claim 1,wherein the controller comprises control features for a variable pitchpropeller.
 13. The electric machine of claim 1, wherein the shaft issupported by the housing with a front bearing and a rear bearing and thefront bearing is a duplex bearing.
 14. The electric machine of claim 1,wherein the shaft comprises a tapered interface for securing a primarymechanical coupling.
 15. The electric machine of claim 1, furthercomprising a rotor positional sensing feature configured for use duringstartup of the machine and the controller is configured to optionallyswitch to a sensorless mode of operation.
 16. The electric machine ofclaim 1, further comprising a rotor positional control feature wherein aposition sensor provides rotational shaft position input to the rotorpositional control feature and the rotor positional control featurepositions the shaft in a selected position when the shaft is stopped.17. The electric machine of claim 1, wherein one of the rotor and statorcomprises protruding magnets.
 18. An electric machine, comprising: ahousing; a stator and a rotor arranged within the housing; a shaftconnected to the rotor and extending out of the housing, the shaftconfigured to be rotationally driven by the rotor or to rotationallydrive the rotor; and an electronic controller configured to controloperations of the stator and rotor and being integrated with thehousing, the electronic controller having an integrated electroniccircuit breaker.
 19. The electric machine of claim 18, furthercomprising a pre-charge feature.
 20. An electric machine, comprising: ahousing; a stator and a rotor arranged within the housing; a shaftconnected to the rotor and extending out of the housing, the shaftconfigured to be rotationally driven by the rotor or to rotationallydrive the rotor; and an electronic controller configured to controloperations of the stator and the rotor and being integrated with thehousing, the electronic controller having an insulation monitorconfigured for identifying the presence and source of electricalinsulation deterioration.